Re: [patch v8 6/9] sched: compute runnable load avg in cpu_load andcpu_avg_load_per_task

From: Alex Shi
Date: Sun Jun 09 2013 - 22:01:37 EST

On 06/10/2013 09:49 AM, Gu Zheng wrote:
> On 06/07/2013 03:20 PM, Alex Shi wrote:
>> > They are the base values in load balance, update them with rq runnable
>> > load average, then the load balance will consider runnable load avg
>> > naturally.
>> >
>> > We also try to include the blocked_load_avg as cpu load in balancing,
>> > but that cause kbuild performance drop 6% on every Intel machine, and
>> > aim7/oltp drop on some of 4 CPU sockets machines.
> Hi Alex,
> Could you explain me why including the blocked_load_avg causes performance drop ?

Thanks for review!

the 9th patch has few explanation. like, after the only task got into
sleep in a CPU, there is only blocked_load_avg left, it looks quite big
in short time. that, block it get tasks before sleep, drive task to
other cpu in periodic balance. So, it cause clear load imbalance.

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